This invention relates to fine drive and positioning units and a memory apparatus and more particularly, to fine drive and positioning units and memory apparatus which can realize high speed, high resolution access while being suited for mass production.
The related art memory apparatuses includes, for example, a magnetic disc apparatus 700 as shown in FIG. 14. This apparatus has a floating head mechanism 703 having a magnetic head 702 provided at a tip of a suspension arm 701, a carriage 705 supported on a swing shaft 704 and mounted with the floating head mechanism 703, and a voice coil motor 706 provided on an opposite side to the magnetic head 702. The energization to the voice coil motor 706 causes the magnetic head 702 to swing about the swing shaft 704. The magnetic head 702 floats over the rotating magnetic disc 707.
Present memory apparatuses are rapidly increasing in recording density per unit area. The yearly increase of recording density so far has been approximately 25%. In recent years, however, it has reached as high as around 60%. Due to this, there is a demand for a head positioning mechanism that is capable of accessing at high speed and with high resolution. For such demand, technologies have been developed that include, for example, two voice coil motors for reducing the force of translation acted on a swing shaft and a two-staged actuator for providing rough and fine movements.
In the related art memory apparatus 700 shown in FIG. 14, however, there has been a problem in realizing high speed, high resolution access because the entire apparatus is vibrated due to a seek reaction force, thus increasing seek time. Meanwhile, it is a general practice to use a memory apparatus by switching over between seek and following control systems, in order to realize high speed seek and accurate track following. However, the switching between the control systems has posed a problem of time loss due to prolonged positioning time.
Meanwhile, in order to solve the above problem, a piggyback type magnetic disc has been proposed which is arranged with a voice coil motor between a suspension arm and a carriage (International Conference on Micromechatronics for Information and Precision Equipment, Tokyo, Jul. 20-23, 1997: MR-08 DEVELOPMENT OF INTEGRATED PIGGYBACK MILLI-ACTUATOR FOR HIGH DENSITY MAGNETIC RECORDING: Shinji KOGANEZAWA, etc., FUJITSU LIMITED).
The structure of this magnetic disc apparatus is shown in FIG. 15. This magnetic disc apparatus 800 is structured by a positioning voice coil motor 803 arranged between a carriage 801 and a suspension arm 802. The carriage 801 is mounted, at its one end, with a stator shaft 804. Also, the carriage 801 is fixed with a magnet 805. Furthermore, a coil 806 is provided opposite to this magnet 805. The coil 806 is fixed on a head mounting block 807. The head mounting block 807 is fixed on a cross shaped spring 808 of the suspension arm 802. The cross shaped spring 808 is fabricated from an extremely thin steel sheet. Meanwhile, the cross shaped spring 808 at its center is spot-welded with the stator shaft 804. At a tip of the suspension arm 802, a gimbal 809 is formed. A slider (not shown) provided with a magnetic head is attached to an underside of the gimbal 809. This magnetic disc apparatus 800 realizes seek time reduction due to short seek operation by the voice coil motor 803.
However, there is a problem that this magnetic disc apparatus 800 requires an increased number of complicated and delicate parts and is thus not suited for mass production. Furthermore, because in the magnetic disc apparatus 800 the head mounting block 807 and the suspension arm 802 are made as movable parts, there is an increase in mass resulting in an increase of a seek reaction force. As a result, there has been a problem with limitation in seek time reduction.
It is therefore an object of the present invention to provide a memory apparatus and fine positioning unit which is capable of realizing access at high speed and with high resolution and which is suited for mass production.
A first fine drive unit in accordance with the present invention in order to achieve the above mentioned object, comprises: a suspension arm for supporting a head portion formed on a slider; a rotation support portion for supporting one portion of the suspension arm and allowing the suspension arm to swing about the support portion; a support member arranged opposite to the suspension arm; a coupling portion provided on the support member and coupled to the suspension arm; a spring portion provided between the support member and the coupling portion; a fine head drive section having bi-directional cantilevers each having one fixed end and the other free end formed on the support member and piezoelectric members respectively provided on the cantilevers; and wherein the cantilevers are vibrated by applying a particular frequency of voltage to the piezoelectric members to cause the cantilevers to contact with the suspension arm thereby finely drive the head portion.
The application of a particular frequency of voltage to the piezoelectric members causes the piezoelectric members to expand and contract thereby vibrating the cantilevers. The suspension arm arranged oppositely to the support member continuously contacts with the cantilevers due to the vibration of the cantilevers. The suspension arm is given a divisional force acted sideways due to contact of the cantilevers. The suspension arm is coupled to the support member through the coupling portion. Because the coupling portion is held by the spring portion, the spring portion is elastically deformed by the sideways divisional force, causing the suspension arm to swing. The head section is moved by the suspension arm swing. The cantilevers are bi-directionally provided and accordingly the head section is capable of moving in opposite directions. As will be referred to later, a piggyback schemed memory apparatus can be structured by mounting the fine drive unit on a carriage driven by a voice coil motor.
A second fine drive unit in accordance with the invention, comprises: a support portion formed integrally with a coupling portion in an island form, a spring portion connected to the coupling portion and bi-directional cantilevers each having one fixed end and the other free end, wherein piezoelectric members are provided respectively for the cantilevers, and a rotation support portion being provided to support one portion of the suspension arm to allow the suspension arm to swing about the support portion; a head section formed on a slider to record data to a memory medium and reproduce data recorded in the memory medium; a suspension arm arranged opposite to the support member and supporting the head section; and wherein the cantilevers are vibrated by applying a particular frequency of voltage to the piezoelectric members to cause the cantilevers to contact with the suspension arm thereby finely drive the head portion.
This fine drive unit is integrally formed with the coupling portion, spring portion and cantilevers of the support member so that the suspension arm is provided on the coupling portion, thus enabling batch process and reducing the number of parts. This is suited for mass production. Also, if the piezoelectric members or rotation support portion are integrally formed, the production process will be further simplified.
In this fine drive unit, the application of a particular frequency of voltage to the piezoelectric members causes the cantilevers to vibrate similarly to the above, thereby swing the suspension arm that is arranged opposite to the support member. The suspension arm is coupled to the support member through the coupling portion, and the coupling portion is held by the spring portion. Accordingly, the spring portion is elastically deformed by the sideways divisional force due to the cantilever. This makes it possible to swing the suspension arm.
A first fine positioning unit in accordance with the invention, comprises: a first fine drive unit; a carriage provided at one end of a support member forming the fine drive unit; a head drive section provided on the carriage to drive the head section by using a magnetic circuit and a coil; and wherein the head section is finely positioned by operation of the fine drive unit and the head drive section.
Also, a second fine positioning unit in accordance with the invention, comprises: a second fine drive unit; a carriage provided at one end of a support member forming the fine drive unit; a head drive section provided on the carriage to drive the head section by using a magnetic circuit and a coil; and wherein the head section is finely positioned by operation of the fine drive unit and the head drive section.
In the first and second fine positioning units, the head drive section uses a magnetic circuit and coil to drive the head section, thus being suited for large movement. The fine head drive section drives the head section through cantilever vibration and is accordingly suited for fine movement. The use of the head drive section and fine head drive section can efficiently effect fine positioning operation over a wide swing range. For example, large swing motion is performed by the head drive section while fine positioning operation is by the fine head drive section. Also, the head drive section and the fine head drive section may be used together. Furthermore, because two actuators for the head drive section and fine head drive section are used in control, there is no necessity of switching in control for between large swing motion and fine positioning operation. Also, because movable portion (suspension arm) can be reduced in mass, it is possible to suppress low the reaction force due to inertia during positioning. Furthermore, the comparatively simple structure is suited for mass production.
Meanwhile, in the second fine positioning unit, the coupling portion, spring portion and cantilevers of the support member are integrally formed to have a suspension arm on the coupling portion, making possible batch process and reduces the number of parts. This is suited for mass production. Also, if the piezoelectric members and the rotation support portion are integrally formed, the manufacture process can be further simplified.
A first memory apparatus in accordance with the invention, comprises: a first fine drive unit; a recording medium for recording data; and wherein data recorded in the memory medium is reproduced and data is recorded through the head section forming the fine drive unit.
Also, a second memory apparatus in accordance with the invention, comprises: a second fine positioning unit; a recording medium for recording data; and wherein data recorded in the memory medium is reproduced and data is recorded through the head section forming the fine drive unit.
The application of a particular frequency of voltage to the piezoelectric members causes the piezoelectric members to expand and contract, vibrating the cantilevers. The suspension arm arranged oppositely to the support member continuously contacts with the cantilevers due to the vibration of the cantilevers. The suspension arm is given a divisional force acted sideways due to the contact with the cantilevers. The suspension arm is coupled to the support member through the coupling portion. Because the coupling portion is held by the spring portion, the spring portion is elastically deformed by the sideways divisional force. This causes the suspension arm to swing. The head section is moved by the suspension arm swing. The cantilevers are bi-directionally provided and accordingly the head section is capable of moving in opposite directions. A piggyback schemed memory apparatus can be structured by mounting the fine positioning unit on a carriage driven by a voice coil motor.
The head drive section is suited for large movement because a magnetic circuit and coil are used to drive the head section. The fine head drive section is suited for fine movement because cantilever vibration drives the head section. The use of the head drive section and fine head drive section enables seek and following operations with efficiency. For example, seek operation is performed by the head drive section while following operation is by the fine head drive section. Also, the head drive section and the fine head drive section may be used together to carry out seek or following operation. Furthermore, because two actuators for the head drive section and fine head drive section are used in control, there is no necessity of switching between seek control and following control. Also, because the movable portion (suspension arm) can be reduced in mass, it is possible to suppress the seek reaction force low. Furthermore, an arm of a piggyback scheme can be structured by a comparatively simple structure, thus suited for mass production.
Meanwhile, in the second memory apparatus, the coupling portion, spring portion and cantilevers of the support member are integrally formed to have a suspension arm on the coupling portion, making possible batch process and reduces the number of parts. This is suited for mass production. Also, if the piezoelectric members and the rotation support portion are integrally formed, the manufacture process can be further simplified.